This invention relates to a receiver for a code division multiple access system, such as a spread spectrum communication system.
The spread spectrum communication system spreads its spectrum in a wide area by use of a spread code sequence having a frequency band width which is far wider than that of the base band signal which after information, such as voice signals to be transmitted have been supplied with proper modulation, such as PSK or FM modulation, so as to compose the base band signal. At the receiving side, the same code sequence as that noted above is generated to search for correlation with the received signal while incrementally moving the code sequence little by little. Next, upon the detection of a correlation (i.e.--the synchronization between the transmitting and receiving codes), the search operation comes to a halt and a code tracking circuit for maintaining the synchronous condition operates so as to enable the system to remain in the communicating condition. In this instance, if a large time lag exists between the detection of a correlation and the stopping of the search, during this period there is a possibility that the search will be advanced until a non-synchronous condition occurs. In order to solve the abovenoted problem, it has been proposed that the search speed be reduced in consideration of the abovenoted time lag; however, under such a condition, it takes much time for synchronizing long transmitting codes that it is impossible to effect a high speed synchronization.